 const uuid = (len, radix) =>{ 
    var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split(''); 
    var uuid = [], i; 
    radix = radix || chars.length; 
    
    if (len) { 
      // Compact form 
      for (i = 0; i < len; i++) uuid[i] = chars[0 | Math.random()*radix]; 
    } else { 
      // rfc4122, version 4 form 
      var r; 
    
      // rfc4122 requires these characters 
      uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-'; 
      uuid[14] = '4'; 
    
      // Fill in random data.  At i==19 set the high bits of clock sequence as 
      // per rfc4122, sec. 4.1.5 
      for (i = 0; i < 36; i++) { 
        if (!uuid[i]) { 
          r = 0 | Math.random()*16; 
          uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r]; 
        } 
      } 
    } 
    
    return uuid.join(''); 
} 
module.exports = {
    uuid:uuid
}